Thermal behavior, kinetics and fast pyrolysis characteristics of palm oil: Analytical TG-FTIR and Py-GC/MS study

Abstract

In this work, the palm oil was selected as the model compound of waste cooking oil and the pyrolysis experiments were performed first by TG-FTIR and then via Py-GC/MS. TG-FTIR analysis showed that the temperature range of palm oil pyrolysis was 385.2 °C–488.4 °C and the volatile products were mainly CO, CO2 and a large number of light hydrocarbon. According to kinetic analysis, palm oil pyrolysis followed the 1.5 order reaction model. The apparent activation energy and pre-exponential factor calculated by Coats-Redfern method were 275.257 KJ mol−1 and 4.252 × 1020 s−1. The fast pyrolysis experiments were performed at different final temperatures (500 °C, 550 °C, 600 °C, and 650 °C) and different heating rates (0.2 °C ms−1, 1 °C ms−1, 5 °C ms−1 and 10 °C ms−1). The GC/MS analysis indicated that the pyrolysis products mainly included saturated hydrocarbons, unsaturated hydrocarbons, aromatic hydrocarbons, carbonyl compounds and other oxygenates. As the final temperatures increased, the relative content of carbonyl compounds decreased and the yields of unsaturated hydrocarbons showed a fluctuant trend. The undesirable aromatic compounds were only detected at 600 °C and 650 °C. As the heating rate increased, the yields of carbonyl compounds increased, while the yields of unsaturated hydrocarbons decreased. The possible fast pyrolysis pathway of palm oil showed that palm oil underwent a series of parallel reactions and continuous reactions to form the final products. The most suitable reaction conditions of palm oil pyrolysis should be further determined by the production purpose and detailed technical and economic analysis.